A thin convex lens has a focal length of 20 cm. When an object is placed in front of the lens, a 3 times enlarged erect image is obtained.
a. State whether the image is real or virtual. Give a reason.
b. Calculate the distance of the object from the lens.
c. Find the distance of the image from the lens.
d. If the height of the object is 2 cm, determine the height of the image.